Prescribed fire is used in the Sudanian savanna-woodland of West Africa as a forest management tool. An experiment was carried out to assess the effects of season of burning, and different vertical probe positions on ...Prescribed fire is used in the Sudanian savanna-woodland of West Africa as a forest management tool. An experiment was carried out to assess the effects of season of burning, and different vertical probe positions on maximum fire temperature and temperature residence time above 60℃ which is considered lethal for plant tissues. Seasons of burning considered were： an early season fire set at the beginning of the dry season （beginning of December）, mid-season fire set at the peak of the dry season （mid-January）, and a late season fire at the end of the dry season （end of March）. The effects of these fires on the germination of buried seeds of three socio-economically valuable tree species were also examined. Results indicated significant differences in maximum fire temperature and residence time with respect to season of burning and vertical probe position （p 〈 0.001）. The highest and longest lasting temperatures were observed at 20 cm above ground during early fire and at the soil surface during mid-season and late fires. This, in turn, affected germination responses of seeds buried at different soil depths. Implications of these findings in the current management practices are discussed.展开更多
Cassava is an important starchy root crop and a major staple for more than 70 million people in Nigeria. New yellow-fleshed genotypes are being developed to combat vitamin A deficiency. Trials of 18 yellow-fleshed gen...Cassava is an important starchy root crop and a major staple for more than 70 million people in Nigeria. New yellow-fleshed genotypes are being developed to combat vitamin A deficiency. Trials of 18 yellow-fleshed genotypes and two officially released white-fleshed clones, used as checks for 2008/2009 and 2009/2010 seasons in five major cassava growing agroecological zones of Nigeria. The trial locations were Ikenne （humid forest）, Ibadan （forest-savanna transition）, Ubiaja （subhumid forest）, Mokwa （southern Guinea savanna） and Zaria （northern Guinea savanna）. At each location, the trial was established in a randomized complete block design with four replications. The objective of the study was to assess genotype performance and genotype ~ environment interaction for total carotene concentration （TCC）, total carotene content per root （TC-R）, and total carotene content per plant （TC-P）. Significant differences （P 〈 0.001） among genotypes, environments and genotype x environment interaction for all the traits evaluated were observed. For TCC, TC-R and TC-P, the best genotypes across the 10 environments were TMS I051601, TMS 1050311, and TMS 1050998. Variation among genotypes accounted for most of the Total Sum of Squares for TCC （67.9%）, TC-R （39.0%） and TC-P （35.9%）. These characteristics of total carotene were also highly correlated. This study revealed that cassava with total carotene concentration can be assessed using either the TCC, or the TC-R, or the TC-P.展开更多
基金supported by the Swedish International Development Cooperation Agency (Sida)
文摘Prescribed fire is used in the Sudanian savanna-woodland of West Africa as a forest management tool. An experiment was carried out to assess the effects of season of burning, and different vertical probe positions on maximum fire temperature and temperature residence time above 60℃ which is considered lethal for plant tissues. Seasons of burning considered were： an early season fire set at the beginning of the dry season （beginning of December）, mid-season fire set at the peak of the dry season （mid-January）, and a late season fire at the end of the dry season （end of March）. The effects of these fires on the germination of buried seeds of three socio-economically valuable tree species were also examined. Results indicated significant differences in maximum fire temperature and residence time with respect to season of burning and vertical probe position （p 〈 0.001）. The highest and longest lasting temperatures were observed at 20 cm above ground during early fire and at the soil surface during mid-season and late fires. This, in turn, affected germination responses of seeds buried at different soil depths. Implications of these findings in the current management practices are discussed.
文摘Cassava is an important starchy root crop and a major staple for more than 70 million people in Nigeria. New yellow-fleshed genotypes are being developed to combat vitamin A deficiency. Trials of 18 yellow-fleshed genotypes and two officially released white-fleshed clones, used as checks for 2008/2009 and 2009/2010 seasons in five major cassava growing agroecological zones of Nigeria. The trial locations were Ikenne （humid forest）, Ibadan （forest-savanna transition）, Ubiaja （subhumid forest）, Mokwa （southern Guinea savanna） and Zaria （northern Guinea savanna）. At each location, the trial was established in a randomized complete block design with four replications. The objective of the study was to assess genotype performance and genotype ~ environment interaction for total carotene concentration （TCC）, total carotene content per root （TC-R）, and total carotene content per plant （TC-P）. Significant differences （P 〈 0.001） among genotypes, environments and genotype x environment interaction for all the traits evaluated were observed. For TCC, TC-R and TC-P, the best genotypes across the 10 environments were TMS I051601, TMS 1050311, and TMS 1050998. Variation among genotypes accounted for most of the Total Sum of Squares for TCC （67.9%）, TC-R （39.0%） and TC-P （35.9%）. These characteristics of total carotene were also highly correlated. This study revealed that cassava with total carotene concentration can be assessed using either the TCC, or the TC-R, or the TC-P.
